Three men sit in a dark room. One sits mostly in the shadows, spinning a globe menacingly. Guess these are going to be our villains.
Baron Vladimir Harkonnen tells the other two, Piter and Feyd-Rautha, about the globe. It's the planet Arrakis—also known as Dune—and it's the planet where the Baron will finally defeat his archenemy, Duke Leto Atreides. Yep, definitely our villains.
Harkonnen and company receive a letter from Duke Leto just then, informing the Baron that his invitation for a meeting has been refused.
Not that the Baron is surprised. As Piter points out, he was simply offering the invitation as a way to keep with tradition.
The Baron says he doesn't just want to destroy Leto; he also wants Leto to know it was the Baron who devised his entire undoing. Got to love the old-fashioned bad-guy dialogue.
Talk turns to Feyd-Rautha, the Baron's impatient nephew. The Baron asks his nephew to observe their Mentat, Piter. Piter is a calculating machine housed in a human body, but the human body is a serious drawback.
In Piter's case, his body is addicted to the Spice Mélange of Arrakis. The Baron can tell, because Piter's eyes are blue on blue with no whites in them. And since he's human, Piter can err.
After putting Piter on display, the Baron asks the Mentat to outline their plans, a.k.a. the novel's plot, to destroy Leto. Feyd-Rautha gets excited by the prospect, finally feeling like the Baron's heir.
The plan is simply complex. Duke Leto will go to Arrakis and set up his capital in the city of Arrakeen. They've already planned to make an attempt on Paul's life. The attempt may succeed, but it does not matter to their plans either way.
Then Hawat, head of security, will look for a double agent in the house. The obvious suspect will be Dr. Yueh, but his Imperial Conditioning will make it seem impossible to everyone. Before Yueh, no one has been able to subvert Imperial Conditioning (for whatever reason).
This will turn Hawat's attention away from Yueh, the true traitor, and toward Lady Jessica. Again, we aren't told why; best to just go with it.
At the correct moment, Yueh will betray the Duke right when the Baron attacks with the Emperor's own Sardaukar units. Those Sardaukar guys are the best of the best.
This is a huge secret. If word ever reaches the other Houses, they may decide the Harkonnen House is too great a threat and unite with the Atreides instead.
If Leto and his family try to flee, their path will be blocked by the planet's ecologist, one Dr. Kynes.
In other words, the Baron and Piter have thought of everything.
Then the Harkonnens will control Arrakis, gain a dictatorship within the CHOAM company, and control the spice trade. What that essential boils down to is: money, money, money. MONEY.
The Baron comes out of the shadows to reveal himself as a huge man who must travel by portable suspensors because of his girth. The thought of defeating Leto really works him up, so he sends for some food.